Our previous study demonstrated increased expression of Heat shock protein (Hsp) 90 in the skin of patients with systemic sclerosis (SSc). We aimed to evaluate plasma Hsp90 in SSc and characterize its association with SSc-related features. Ninety-two SSc patients and 92 age-/sex-matched healthy controls were recruited for the cross-sectional analysis. The longitudinal analysis comprised 30 patients with SSc associated interstitial lung disease (ILD) routinely treated with cyclophosphamide. Hsp90 was increased in SSc compared to healthy controls. Hsp90 correlated positively with C-reactive protein and negatively with pulmonary function tests: forced vital capacity and diffusing capacity for carbon monoxide (DLCO). In patients with diffuse cutaneous (dc) SSc, Hsp90 positively correlated with the modified Rodnan skin score. In SSc-ILD patients treated with cyclophosphamide, no differences in Hsp90 were found between baseline and after 1, 6, or 12 months of therapy. However, baseline Hsp90 predicts the 12-month change in DLCO. This study shows that Hsp90 plasma levels are increased in SSc patients compared to age-/sex-matched healthy controls. Elevated Hsp90 in SSc is associated with increased inflammatory activity, worse lung functions, and in dcSSc, with the extent of skin involvement. Baseline plasma Hsp90 predicts the 12-month change in DLCO in SSc-ILD patients treated with cyclophosphamide.

Objective: Hedgehog signaling not only plays crucial roles during human development but also has been implicated in the pathogenesis of several diseases in adults. The aim of the present study was to investigate the role of the hedgehog pathway in fibroblast activation in systemic sclerosis (SSc).Methods: Activation of the hedgehog pathway was analyzed by immunohistochemistry and real‐time polymerase chain reaction (PCR). The effects of sonic hedgehog (SHH) on collagen synthesis were analyzed by reporter assays, real‐time PCR, and Sircol assays. Myofibroblast differentiation was assessed by quantification of α‐smooth muscle actin and stress fiber staining. The role of hedgehog signaling in vivo was analyzed by adenoviral overexpression of SHH and using mice lacking 1 allele of the gene for inhibitory receptor Patched homolog 1 (Ptch^+/− mice).Results: SHH was overexpressed and resulted in activation of hedgehog signaling in patients with SSc, with accumulation of the transcription factors Gli‐1 and Gli‐2 and increased transcription of hedgehog target genes. Activation of hedgehog signaling induced an activated phenotype in cultured fibroblasts, with differentiation of resting fibroblasts into myofibroblasts and increased release of collagen. Adenoviral overexpression of SHH in the skin of mice was sufficient to induce skin fibrosis. Moreover, Ptch^+/− mice with increased hedgehog signaling were more sensitive to bleomycin‐induced dermal fibrosis.Conclusion: We demonstrated that the hedgehog pathway is activated in patients with SSc. Hedgehog signaling potently stimulates the release of collagen and myofibroblast differentiation in vitro and is sufficient to induce fibrosis in vivo. These findings identify the hedgehog cascade as a profibrotic pathway in SSc.

Background Dermal fibroblasts from patients with systemic sclerosis (SSc) release excessive amounts of collagen resulting in tissue fibrosis. The molecular mechanisms underlying this pathological activation are incompletely understood. Objective To investigate whether Notch signalling contributes to the uncontrolled activation of fibroblasts in SSc. Methods Activation of the Notch pathway was assessed by immunohistochemistry or Western blot for the Notch intracellular domain and the Notch ligand Jagged-1 (Jag-1) and real-time PCR for the target gene hes-1. Differentiation of resting dermal fibroblasts into myofibroblasts was assessed by staining for α-smooth muscle actin. The synthesis of collagen was quantified by real-time PCR and Sircol assays. Results Notch signalling was activated in lesional skin of patients with SSc. The activation persisted in cultured dermal SSc fibroblasts. Stimulation of healthy dermal fibroblasts with recombinant human Jag-1-Fc chimera resulted in an SSc-like phenotype with increased release of collagen and differentiation of resting fibroblasts into myofibroblasts. Consistent with the selective activation of the Notch pathway in dermal SSc fibroblasts, DAPT or siRNA against Notch strongly reduced the basal collagen expression in SSc fibroblasts, but not in fibroblasts from healthy volunteers. Conclusion It was shown that Notch signalling is activated in SSc and plays an important role in fibroblast activation and collagen release. Inhibition of Notch signalling might be an effective strategy to selectively prevent the aberrant activation of SSc fibroblasts.